The present invention relates to a fuel oil injector, more particularly, to a solenoid-operated injector for an electronically controlled fuel oil injection system, which serves a solenoid-operated injector to control fuel oil injection by means of moving a ball valve set.
The electronically controlled fuel oil injection system shown in FIG. 1 includes an injector 100 designed to have a solenoid-operated injector which serves to control the time of starting injection, the duration of injection and the time of stopping injection in response to a current pulse transmitted from an electronic control unit 200. As soon as the solenoid-operated injector is activated to the open position, fuel oil is injected under the pressure. As the solenoid valve is closed, fuel oil injection is stopped. As a result, the electronic control unit 200 can control the time for the injection start and stop, and, by controlling the duration of the current pulse, it can also control the injection volume q (cc/time) of fuel oil per cycle.
Fuel oil pressure is established by the fuel pump 300 and controlled by the pressure regulator 400.
At present, the injector applied to a gasoline engine injection system is mostly designed as a solenoid-operated injector. Such an injector is represented by U.S. Pat. No. 4,662,567. However, the idea of design for the valve assembly at its leading end is generally based upon the model of a diesel injector, including a valve needle and a valve body. The start/stop of fuel oil injection is controlled by means of a movement of the valve needle which is precisely fitted inside the valve body. Consequently, both the valve needle and the valve body must be manufactured with a high degree of precision and a resultant high cost, and, in particular, the deep and long inner hole of the valve body, as well as the cone in the deep hole, must be manufactured with very expensive, close tolerance machinery. Owing to that, the above-mentioned common injector has been an expensive element of the known fuel injection systems.
In addition, in common injectors, the processing error always causes different dynamic responses as the various valve bodies open or close; as a result, the injection volume per cycle fails to be maintained with accuracy, with specification injections doing the same.